tatbaird:

 

Yeah, you could use several mesh capable access points, but would be too expensive probably.

 

yup.

I just put in one of these TP-LINK TL-WPA4220KIT ADVANCED AV500 Wi-Fi Powerline Extender Starter Kit with 2 LAN Ports, Up to 300Mbps Wireless, and they work very well for the added wireless access point -- the deal with PBTech was buy one of these, get 2 more wired access points for free via redemption -- which are on the way to me now.  The Amazon advert for these is actually on the Geekzone page for this post.  They aren't passthrough, but it's easy (and useful) to replace single or double outlets with a quad outlet.

I tried three types of powerline adapter in our house and couldn't get acceptable performance out of any of them. 

I found a self employed network tech  (ex Telecom) who has set up as a home network specialist and he carries a few makes so we tried all of them.  Interestingly they were all basically the same technology but there was difference in performance.  All were sub-par but to different extents.